Modeling capillary pressure using capillary bundles with arbitrary cross-sections obtained from photomicrographs

Virnovsky, G.A.; Lohne, Arild; Frette, Olav Inge

doi:10.1016/j.petrol.2009.08.002

Cited by 11 publications

(5 citation statements)

References 23 publications

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“…Two types of methods are adopted for representing the cross-sections of the straight tube model. The first representation method is cross-sections with analytical angular geometries and a pore size distribution function (Kovscek et al, 1993;Ma et al, 1996;van Dijke et al, 2004;Helland & Skjaeveland, 2006b); the other method is extracted crosssection geometries directly from rock images (Lindquist, 2006;Virnovsky et al, 2009;Glantz & Hilpert, 2011;Kim & Lindquist, 2012). The straight tube model with angular tube cross-sections allow the development of mixed wettability and cross-sectional multiphase configurations and thus are well suited as a basis for developing simple, yet physically-based models accounting for some of the important capillary phenomena that occur in porous media;…”

Section: Motivation and Scientific Contributionsmentioning

confidence: 99%

Dynamic Capillary Pressure Curves From Pore-Scale Modeling in Mixed-Wet-Rock Images

2013

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Summary In reservoir multiphase-flow processes with high flow rates, both viscous and capillary forces determine the pore-scale fluid configurations, and significant dynamic effects could appear in the capillary pressure/saturation relation. We simulate dynamic and quasistatic capillary pressure curves for drainage and imbibition directly in scanning-electron-microscope (SEM) images of Bentheim sandstone at mixed-wet conditions by treating the identified pore spaces as tube cross sections. The phase pressures vary with length positions along the tube length but remain unique in each cross section, which leads to a nonlinear system of equations that are solved for interface positions as a function of time. The cross-sectional fluid configurations are computed accurately at any capillary pressure and wetting condition by combining free-energy minimization with a menisci-determining procedure that identifies the intersections of two circles moving in opposite directions along the pore boundary. Circle rotation at pinned contact lines accounts for mixed-wet conditions. Dynamic capillary pressure is calculated with volume-averaged phase pressures, and dynamic capillary coefficients are obtained by computing the time derivative of saturation and the difference between the dynamic and static capillary pressure. Consistent with previously reported measurements, our results demonstrate that, for a given water saturation, simulated dynamic capillary pressure curves are at a higher capillary level than the static capillary pressure during drainage, but at a lower level during imbibition, regardless of the wetting state of the porous medium. The difference between dynamic and static capillary pressure becomes larger as the pressure step applied in the simulations is increased. The model predicts that the dynamic capillary coefficient is a function of saturation and is independent of the incremental pressure step, which is consistent with results reported in previous studies. The dynamic capillary coefficient increases with decreasing water saturation at water-wet conditions, whereas, for mixed- to oil-wet conditions, it increases with increasing water saturation. The imbibition simulations performed at mixed- to oil-wet conditions also indicate that the dynamic capillary coefficient increases with decreasing initial water saturation. The proposed modeling procedure provides insights into the extent of dynamic effects in capillary pressure curves for realistic mixed-wet pore spaces, which could contribute to the improved interpretation of core-scale experiments. The simulated capillary pressure curves obtained with the pore-scale model could also be applied in reservoir-simulation models to assess dynamic pore-scale effects on the Darcy scale.

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Section: Motivation and Scientific Contributionsmentioning

confidence: 99%

Dynamic Capillary Pressure Curves From Pore-Scale Modeling in Mixed-Wet-Rock Images

2013

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“…Virnovsky et al [40] modeled the void space of porous rock at capillary equilibrium, a bundle of capillary tubes of arbitrary cross-sections taken directly from photomicrographs were used to represent irregular pores. They demonstrated that such reconstructed models can retain important features of realistic pore space geometry, curvature and roughness.…”

Section: Related Work and Motivations 21 Related Workmentioning

confidence: 99%

A simple and effective geometric representation for irregular porous structure modeling

Kou

Tan

2010

Computer-Aided Design

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Please cite the article as follows:Kou, X.Y. and S.T. Tan, A simple and effective geometric representation for irregular porous structure modeling. Computer-Aided Design, 2010. 42(10): p. 930-941. Youtube Video Link:Abstract: Computer-aided design of porous structures is a challenging task because of high degree of irregularity and intricacy associated with the geometries. Most of the existing design approaches either target at designing artifacts with regular-shaped pores or reconstructing geometric models from existing porous objects. For regular porous structures, it is difficult to control the pore shapes and distributions locally; for reconstructed models, a design is attainable only if there are some existing objects to reconstruct from. This paper is motivated to present an alternative approach to design irregular porous artifacts with controllable pore shapes and distributions, yet without requiring any existing objects as prerequisites. Inspired by the random colloidaggregation model which explains the formation mechanism of random porous media, Voronoi tessellation is first generated to partition the space into a collection of compartments. Selective compartments are then merged together to imitate the random colloid aggregations. Through this Voronoi cell merging, irregular convex and concave polygons are obtained and the vertices of which are modeled as control points of closed BSpline curves. The fitted B-Spline curves are then employed to represent the boundaries of the irregular-shaped pores. The proposed approach drastically improved the ease of irregular porous structure modeling while at the same time properly maintained the irregularity that are widely found in natural objects. Compared with other existing CAD approaches, the proposed approach can easily construct irregular porous structures which appear more natural and realistic.

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“…Studies have also been conducted on the simulation of the drainagetype displacements based on the quasi-static pore-scale approach (Hilpert and Miller, 2001), model considering phase trapping (Bryant and Johnson, 2003), invasion percolation model (Neuweiler et al, 2004), bundle of tubes model (Helland and Skjaeveland, 2006;Virnovsky et al, 2009), medial axis analysis (Lindquist, 2006), mathematical relationships for the removal of the wetting liquids (Mayer and Stowe, 2006), quasi-static displacements (Prodanović and Bryant, 2006), lattice-Boltzmann pore-scale modeling (Papafotiou et al, 2008), upscaled model derived with the homogenization theory (Vasin et al, 2008), aperture-scale simulation using level set method , and the grain-based model within fractional-wet porous media (Motealleh et al, 2009).…”

Section: Latest Developments After the Year 2000mentioning

confidence: 99%

“…Peng et al (2009) Explained how to select correct critical curvatures for pore level events. Virnovsky et al (2009) Developed a two-phase flow model, including bundle of capillary tubes having arbitrary cross-sections, for capillary equilibrium condition. Yadali Jamaloei and Kharrat (2010a) Proposed new mechanisms for low-IFT drainage in an oil-wet medium filled with heavy oil and brine, which is flooded by a surfactant solution.…”

Section: Author (S)mentioning

confidence: 99%

Pore-scale events in drainage process through porous media under high- and low-interfacial tension flow conditions

Jamaloei

Kharrat

Asghari

2010

Journal of Petroleum Science and Engineering

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Modeling capillary pressure using capillary bundles with arbitrary cross-sections obtained from photomicrographs

Cited by 11 publications

References 23 publications

Dynamic Capillary Pressure Curves From Pore-Scale Modeling in Mixed-Wet-Rock Images

Dynamic Capillary Pressure Curves From Pore-Scale Modeling in Mixed-Wet-Rock Images

A simple and effective geometric representation for irregular porous structure modeling

Pore-scale events in drainage process through porous media under high- and low-interfacial tension flow conditions

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